Band type metal finishing and grinding machines, and the like



www; L i956 H. WHITE-:SELL Er AL 2,757,49

BAND TYPE METAL FINISHING AND GRINDING MACHINES, AND THE LIKE 8 Sheets-Sheet l Filed April 3, 1955 H WHITESELL Er A1. 2,757490 BAND TYPE METAL F'INISHING AND GRINDING MACHINES, AND THE LIKE Filed April 3. 1953 @u mm s sheets-sheet 3 m., 7, 1956 H. wHn'EsELl. Er AL BAND TYPE METAL FINISHING AND GRINDING MACHINES, AND THE LIKE Filed April s, 1953 7, 1956 H. wHlTEsl-:LL Er AL 23579490 BAND TYPE METAL FINISHING AND GRINDING MACHINES, AND THE LIKE Filed April 5, 1953 8 Sheetsheet 4 H. wHlTEsl-:LL ET AL 2,757,490

Aug., 7, 1956 BAND TYPE METAL FINISHING AND GRINDING MACHINES, AND THE LIKE 8 Sheets-Sheet 5 Filed April 3, 1955 aa/ F735? 56 8 FTSf'll.

In venia rs:

- HorryWhTeSeH Ef Aug 7, 1956 H. wHlTEsl-:LL ET AL 2,757,490

BAND TYPE METAL. FINISHING AND GRINDING MACHINES, AND THE LIKE 8 Sheets-Sheet 6 Filed April 3, 1953 M' eMoTh hn )L 7, 1956 H. wHrTEsELL Er AL 2,757,490 BAND TYPE METAL FINISHING AND GRINDING MACHINES, AND THE LIKE Filed .April 5, 1955 a sheets-sheet "r Mike Mmm ug- 7, 1956 H. wHn'EsELL. ET A1. 2,757,490

BAND TYPE METAL FINISHING AND GRINDING MACHINES, AND THE LIKE Filed April 5, A1953 8 Sheets-Sheet 8 BAND TYPE MlETAL lFINlSHiNG AND GRINDING MACK-UNIES, AND THE LIKE Harry Whitesell and lvllilte Matheu, Chicago, lli.

Application April 3, 1953, Serial No. 346,654

i4 Claims. (Cl. Sl-MS) This invention relates to improvements in band type metal finishing and grinding machines, and the like. That is, the invention relates to improvements in that type of finishing and grinding machines in which the polishing or grinding operation is performed by contact of the article against the rapidly travelling abrasive surface of a suitable band or belt. The operation, whether a grinding or a finishing operation thus embodies the use of a travelling band or belt surface of abrasive nature. The band or belt travels over two pulleys, one being the contact wheel and the other being an idler, and the abrasive operation is performed by holding the article against that portion of the band which travels around and on the contact wheel. The width of the abrasive band and its speed of linear travel are adjusted largely according to the nature of the work in hand, the metal being treated, the size of the` article being treated, and various factors of the operation. ln general it may be noted that the linear speeds are high, being from a few thousand feet per minute to as high as fifteen or more thousand feet per minute. The band width will vary from a few inches to as much as twelve or fifteen inches or more.

Usually the contact wheel, which may also be, and frequently is, the driving wheel, will have an axial length parallel to its axis, as great as or greater than the band width, so that the full width of the band is afforded a supporting surface at the location of such wheel. Furthermore, this contact or driving wheel is generally if not invariably of uniform diameter, so that by pressing the article to be treated against the band riding over or adjacent to such wheel the full width of the band may be used for the operations. The wheel diameter may be of size satisfactory for the intended operations. Such size may be between, say four inches and fifteen inches, or larger, depending on the operations. The idler wheel is usually crowned, and such wheel should be a crowned wheel when using the features of invention presently to be disclosed, in order to secure best operation; butisuch crowning is not necessary in all cases, and we do not intend to limit ourselves to a crowned wheel construction, except as we may do so in the claims which will follow.

The tension te which the band is subjected during the abrading operations materially affects both the running of such band and the abrasive effects thereof. Furthermore, the band is subject to stretch, and after operation for a length of time some set may occur in the band so that its stretch becomes permanent. Thus the band length increases after an interval of operation. Means must be provided for developing in the band such an amount of tension as is desired for the operation in hand, and means must be provided for controlling and regulating the amount of that stretch as required from time to time. One principal object of our present invention relates to the provision of means under control of the operator for regulating the band tension as desired by the operator, and for maintaining a substantially constant tension at the regulated value during the operation, and

atent O rice until such tension is again intentionally changed by the operator.

In connection with the foregoing stated object we have also provided spring tension means to maintain the band tension at the adjusted value while .at the same time permitting slight movements of the idler wheel towards and from the driving or contact wheel, such results being secured by the provision of yieldahle spring means acting to urge the idler wheel in the proper direction for such result. ln connection with the foregoing we have also made provision for quickly releasing the idler wheel carrier, allowing sufficient movement of the idler wheel towards the driving or contact wheel to enable removal and replacement of the abrasive band, or for the purpose of making any other adjustments which may be desirable or required from time to time.

As is well known a band or belt travelling over a crowned wheel will tend to ride to the: crown of such wheel, so that it rides such crown with equal band widths at both sides of the crown of the wheel. Accordingly, if such a wheel be shifted laterally--that is, along its axis and normal to the direction of band travel, the crowning effect of such wheel will urge the travelling band to follow such lateral wheel shift so as to maintain the proper ride on the wheel crown. This fact affords us the means whereby we may control the lateral positioning of the band during its travel over the two wheels, and without need of contacting the edge of the band itself in order to effect such lateral control. One principal feature and object of our present invention concerns itself with the provision of simple and very effective means to effect such lateral shift of the idler wheel, while maintaining the band under its adjusted or intended tension.

Such lateral shift of the idler wheel may be effected without change of the direction of its axis, so that the plane which includes the wheel crown is then shifted without tilt of such plane, and always parallel to its previous positions. Or, the lateral shift of the idler wheel may be effected while at the same time rocking the axis of such wheel slightly within a plane which includes the wheel axis. Thus, by rocking the wheel axis within a plane which lies substantially normal to the direction of band travel the distance between the points of tangency of the band with the two wheels will not be changed during such rock, and thus the rocking adjustment may be made without change of band ten sion. When the idler wheel axis is subjected to such rocking movement during its lateral shift it will be evi dent that the band will be subjected to a slight twist in its runs between the two wheels, but when using bands of acceptable length, with the separation between the wheels amounting to several wheel diameters, as is usually the case under good operating conditions, the amount of such twist will be very small when the angle of wheel rock is of the order of say five or six degrees to each side of the normal idler wheel position in which its axis is parallel to the axis of the driver or contact wheel. Under such circumstances the band will continue to run smoothly during shift of the idler wheel laterally while at the same time giving its axis a slight twist as above explained. Thus the lateral adjustment of the idler wheel may be effected with a compound idler wheel adjustment.

By effecting the rock of the axis of the idler wheel in such direction, during the lateral shift ot' such wheel, that the crown on that peripheral portion of the idler wheel is receiving the oncoming band, moves in the direction of idler wheel shift, the effect of urging the band to move over and thus to control the location of vthe band on the driving or contact wheel, is greatly emphasized, and a bettercontrol of the bands travel is effected. We have made provision, and have disclosed the means, to effect lateral shift of the idler wheel, and at the same time to eil'ect such rocking of the axis of the idler wheel; and specifically, we have made 'such provision for effecting such idler wheel rock in a plane substantially normal to the runs of the band so that the length of the band is not disturbed by Isuch adjustments.

ln general the means to effect the foregoing idler wheel adjustments are such that the point of intersection of the wheel axis through the plane which includes the wheel crown, travels in a curved line during the making of the adjustments. The curvature of such line of travel might be a circular arc. Conveniently, however, such curve of point travel is a departure from true circularity, and the rate of curve varies as the adjusting operation progresses. In this connection it is also noted that when the tilting of the idler wheel is effected about a point of intersection of the wheel axis with the plane of the wheels crown, which point of intersection travels along a curved line, the varrangement may be such that both `of the points of tangency of the band with the idler wheel, at top and bottom, shift in the same direction, but at different rates, during the adjusting Operation. That is, there is no tendency for the lower portion of the idler wheel crown to oppose the desired lateral band movement and adjustment due to the retrograde movement of such lower point or portion of tangency of the band on the idler wheel. Both the top and bottom points of band engagement with the idler wheel move in the same direction during any adjusting operation.

We have disclosed and shall describe herein several specitic forms of device by which idler wheel movements and adjustments of the foregoing nature may be effected.

Due to the high linear speeds at which such abrasive bands travel and for other reasons, it is desirable that the operator should have complete control over the running of the band at all times. He `should be able to control the tension developed in the hand as well as the lateral location of travel of the band over the contact wheel where he 1s working. This latter control is especially desirable slnce thereby the operator may be able to cause the band to run on that portion of the Contact or driving wheel which 1s best adapted to the work which he is carrying on. Furthermore, when the band width is the same as the wheel wldth of the driving or contact wheel it is evident that .close control of the running: of such band on such wheel is highly desirable lso that the edge of such band will not lmproperly over-ride the end of the wheel.

It is a further important feature of our present invention to provide the controls for both band tension and band shift laterally, at points convenient to the operator, andthus, rather close to the location of the contact or drlvlng wheel itself. Thereby the operator may effect the desired adjustments from time to time without having to leave his stand, and while himself maintaining his positron at or close to the working stand where he performs his work.

A further feature of our present invention relates to the provision of a design and construction of the idler wheel unit such that the same unit may be used for either a right-hand or a left-hand set-up-that is, a vset-up wherein the idler wheel lies either to the right-hand side of the operator as he faces his work, or to his left-hand Side. To better understand the significance and importance of this relationship the following brief statement of general use and operation of such equipment is made:

Frequently the driving or contact wheel is carried by the end of a shaft which is driven by or constitutes the shaft of the driving motor. The idler wheel of crowned type is carried by a base member which is set away from the said shaft and from the contact wheel the desired distance, and with the crowned idler wheel in alignment with the motor driven contact wheel. Usually the contact wheel is set at an elevation above the door level such as to bring the upper arm of the band to the level where the operator can conveniently bring the work into abrasive contact with such Contact wheel. The idler wheel is then carried at a lower elevation so that the band runs between the two wheels slant downwardly from the Contact wheel to the idler wheel at a convenient angle, say about twenty-tive degrees from the horizontal. The operation is conducted with the driving or contact wheel drawing the band towards such contact wheel on the upper band run, and away from the contact wheel on the lower run. The operator stands facing the contact wheel yat its free side, that is, the side away from the band runs. Thus the operator looks along the upper band run as he stands in his working position. The work to be ab'raded is pressed against the band riding over the upper portion of the contact wheel, or against the band directly in advance of such position where the band is rapidly approaching the contact wheel. In this position the operator look-s along the upper approaching band run, and towards the idler wheel which is located at the lower level. ln this position the operator has a continuously goed view of the condition and location of the band during the operation.

With the above set-up the driving or contact wheel may be located at either the right-hand `side of the driving motor or at the left-hand side of such motor. Usually the set-up is termed a right-hand `operation when the contact wheel is at the right-hand side of the driving motor, and for convenience we have herein illustrated. such a set-up in the drawings. However in many cases it is desirable or necessary to use a left-hand set-up in place of such righthand set-up as illustrated. One feature and object of our present invention relates to the provision of a construction which can be used alternatively for idler wheel operation according to either set-up. The desirability of this will appear from the following explanation:

The crowned idler wheel must be supported in alignment with the contact wheel or be adjustable within a range of adjustments included within such alignment condition. The idler wheel is carried by a rod or shaft which extends in more or less horizontal direction from a stand and without the need of an outboard bearing for such wheel rod or shaft. lt is desirable that such idler wheel shall be on the same side of its supporting stand as is the contact wheel with respect to its driving motor. That is, when using a right-hand set-up, with the contact Wheel at the right-hand side of the driving motor, it is desirable that the idler wheel shall also be located at the right-hand side of the stand whereby it is supported as above explained.

One feature and object of our present invention relates to the' provision of an idler wheel unit which is so designed and constructed that it includes a base section which is set onto and attached to the door, together with a stand or bracket element set onto and secured to such base. T his stand carries the rod or shaft on which the idler wheel is located. We have so arranged the parts that this stand may be readily set onto the base with the idler wheel at either the right-hand or the left-hand position with respect to the base. In this connection we have also made provision for effecting proper adjustments of the position of such stand lengthwise of the base, thus adjusting the distance between the idler wheel and the Contact wheel (for a given location of the base on the floor), and for adjusting the idler wheel laterally with respect to such stand, and with the desired degree of rock during such lateral adjustment, according to the principles already explained. By the foregoing arrangements the idler wheel unit as an entirety may be used as either a right-hand or a lefthand unit according to installation requirements, and without change of structure of the unit itself.

Specifically, we have also herein illustrated and shall describe several embodiments of our invention, includingl alternative constructions for supporting the idler wheel and securing the lateral and rocking movements thereof, and

other alternative constructions as will presently appear.

Other objects and uses of the invention will appear from a detailed description of the same, which consists in the features of construction and combinations of parts hereinafter described and claimed.

In the drawings:

Figure 1 shows a side elevation of an idler wheel unit embodying the features of our present invention, and this figure shows the left-hand elevation of such unit as it has been set up and illustrated;

Figure 2 shows a plan View of the base and stand and other elements of the unit shown in Figure 1, being a view in a plane parallel to the upper face of the base section;

Figure 3 shows an end view corresponding to Figures 1 and 2, looking at that end of the unit which would be farthest removed from the driving or contact wheel; and this figure is taken at right-angles to Figure 2--that is, the surface of the sheet in Figure 3 is normal to the plane of the upper face of the base section shown in Figure 2;

Figure 4 shows an end View corresponding to Figures l, 2 and 3, but looking at the end of the unit opposite to the end shown in Figure 3; and Figure 4 is a view looking at that end of the unit closest to the driving or contact wheel;

Figure 5 shows a fragmentary longitudinal vertical section vertically through the central portion of the base section, being taken on the lines 5-5 of Figures 3 and 4, looking in the directions of the arrows;

Figure 6 shows a cross-section taken on the line 6-6 of Figure 5, looking in the direction of the arrows;

Figure 7 shows a fragmentary horizontal section taken on the lines 7-7 of Figures 3 and 4, looking in the directions of the arrows;

Figure 8 shows a cross-section taken on the line 8 5 of Figure 7, looking in the direction of the arrows;

Figure 9 shows a fragmentary side elevation of the stand or bracket portion of a modified embodiment of our invention, in which modification a different means is provided for effecting lateral and rocking adjustment of the idler wheel, from the previously disclosed means for such operations;

Figure 10 shows a somewhat schematic end View of the modilied construction shown in Figure 9, being an end view looking in the same direction as the view of Figure 3, previously referred to;

Figure 11 shows schematically an elevational view of the set-up of the driving or contact wheel, and the idler crowned wheel to which the present invention generally relates, and this view shows the relation between the two wheels and the runs of the abrasive band, and this view also shows, schematically, the manner in which the controls for band tension and for lateral movement and tilt of the idler crowned wheel may be operated by the operator from his operating stand, and by use of flexible shafting connections, or the like;

Figure l2 shows a plan schematic view corresponding to Figure 11;

Figure 13 shows a fragmentary vertical longitudinal section through another modified form of means to shift the wheel laterally and at the same time produce rock or tilt of the wheel axis;

Figure 14 shows a cross-section taken on the line 14-14 of Figure 13, looking in the direction of the arrows; and

Figure l5 shows a cross-section taken on the line 15--15 of Figure 13, looking in the direction of the arrows;

Referring first to Figures 1l and 12, the driving or contact wheel is designated as 26, and the idler wheel as 21. The contact wheel is carried by a shaft Z2 driven by any suitable drive means, not shown; and such shaft is journalled in bearings away from the observer in Figure 12. Thus said contact wheel is carried by the shaft beyond any bearing of such shaft. The crowned idler wheel 21 is carried by a unit designated in its entirety by the numeral 23. As will presently appear in detail this unit includes the upstanding bracket 24 which carries the rod or shaft on which such wheel is journalled. Preferably the idler wheel is located at a lower elevation above the ti floor level 25 than the contact wheel 20 so that the runs of the abrasive band 26 extend downwardly at some angle from the horizontal between the wheel 20 and the wheel 21. The upper and lower runs of this band are designated as 26a and 26h, respectively, for purposes of convenience in Figure 11. In operation the drive wheel is rotated in such direction that the band travels towards the wheel 20 in its upper run 26a and away from the said wheel in its lower run 26h.

The operator stands adjacent to the contact wheel 20 and to the left thereof, referred to in Figures 11 and 12,

and he faces towards the right, that is, along the run of the band. Under these conditions the two wheels are rotated in the directions shown by the arrows in Figure 1l.

Reference will now be made to Figures 1 to 8 as showing in detail the construction of one form of idler wheel carrier embodying our present invention. Generally said embodiment includes the base section 27, of box like con struction, but open at its top, as well shown in Figures 3 and 4. This base section thus includes the oor 2d, the sides 29 and 3i), and the upper edges of said sides are flanged over as shown at 31 and 32 to provide a means of retaining the carrier against removal upwardly from the base section, as will presently appear. This base section is to be secured to the floor, for which purpose we have shown the angle bar element 33 having one leg secured to the floor of the section 27 in convenient manner, as by the bolts 34 shown in Figures 2 and 3. These pass through slots formed in the floor of the section 27 so that adjustment laterally of the element 33 may be readily effected. This angle bar 33 has its two legs formed at an angle to each other corresponding to the angle at which it is desired to have the base section 27 slant upwardly towards the contact Wheel position. To the other end of the base section there is secured the stand element 35. This conveniently comprises a sheet metal member formed to provide the vertical wall 36, the base plate .37, the side walls 38 and 39, and the supporting plate 40. This supporting plate 40| is formed at such an angle to the base plate 37 that it may seat nicely beneath the end portion of the bottom 28 of the section 27; and the side walls 3S and 39 are formed at such spacing from each other that they may embrace the end portion of the base section 27 between them. Suitable connecting means is provided for securing this stand element to the end por tion of the base section 27. In the form shown such means includes the bolts 41 extended through the plate 4@ and through slots formed in the floor 28 of the sec* tion 27. It is here noted that by locating the slots of the two ends of the floor 23 at proper locations it is possible to set the angle bar and the stand element reversibly at either end of the base section 27. Thus said base section may be set up for slant upwardly from the floor from either of its ends merely by reversing the locations of the angle bar 33 and the stand element 35, end for end of the base section 27.

A carrier element 42 is set into the base section 27 and is movable endwise of such base section but is not removable upwardly from the base section. ln other words, such carrier element is telescoped into the base section. This carrier element comprises a sheet metal element, formed to provide the top 43, the downwardly extending side walls 44 and 45; and the lower edges of these side walls are formed inwardly a short distance to provide the flanges 4e and 47 which provide faces which seat onto and ride on the upper surface of the bottom 28 of the base section. This is well shown in Figures 3 and 4. This carrier is so formed that it will ride nicely back and forth along the base section during controlled adjustments and during the operations of the device.

A threaded shaft 48 extends lengthwise of the base section through its full length or such portion of such length as may be needed to effect the desired endwise shifts of the carrier, 42, as will presently appear. This shaft 48 is journaled in the bracket bearings 49 and 50 extending upwardly from the ooi 28 of the base section; and the end portions of the shaft are shouldered to provide thrust surfaces against the bearings, so that end thrusts of the Shaft will be effectively transmitted to the base section. As shown these bearings are simple lined bearings, but any other suitable bearing design adapted to receive and transmit such thrusts may be used as will meet the requirements of the design. One end (generally that end at the high end of the base section), of this shaft is provided with. suitable means to rotate the shaft under control from a distance (or locally). in the arragement shown the projecting end portion of the shaft is provided with the transverse hole 51 through which may be extended a cott'er pin or other attaching element to connect a flexible shaft section, 52 (see Figure ll) or other remote control device, to the shaft We have also shown the cross bar element 53 connected to the end portion of this shaft close to the bearing w. This cross bar constitutes a supplemental element by which the shaft may be readily rotated by the operator when he is close to the idler unit itself. v

Located within the carrier space, but 'not directly connected to said carrier is the spring box element 54, best shown in Figures and 6. This element includes the top and bottom horizontal plates 55 and 56, and the end walls 57 and 58. All of these parts may be conveniently made from a single blank properly formed and, if desired, having its ends welded or brazed together for added stilfness. This box element is provided with openings in its end walls of sufficient size to accommodate and pass the shaft 48 without interference, as shown in Figure 5. A laterally extending shoe 59 is secured to the bottom 56 of this box element and rides freely on the floor of the base section 27. The lateral projections of this shoe are suicient to effectively retain the box element against rotation with the shaft during adjustments presently to be explained, and to avoid unnecessary binding of the parts during such adjustments. Thus the box element may be shifted endwise of the base section Z7, but is retained against any rotation therein.

Within the box element 5d there is located a nut 60 which is threaded onto the shaft d8. This nut is of size and form such that it may shift endwise within the box element 54, but, being of square form, as shown in Figure 6, it so engages the top and bottom of the box element that the nut is retained against rotating when the shaft is rotated for adjustments. Thus the nut is also prevented from rotation with respect to the base section also. A spring 6l is set around the shaft 48 within the box element and between the nut 6d and the opposite end 57 of the box element. This spring therefore urges the nut against the end 58 of the box clement under a pre-loaded force dependent on the characteristics of the spring. The intention is that normally the box element shall be urged leftward by the spring into a position, along the threaded shaft, such as to bring the end wall 58 of the box element into stopped engagement with the nut 60. Under these conditions the spring is in its most relaxed condition, taking into account the amount of preloading to which the spring has been set in the original installation and assembly of the parts. Rotation of the shaft 4S (without rotation of the nut 60), under these circumstances will cause shift of the box element 54 in the one direction along the base section 27, or the other. in any given location of the box element lengthwise of the base section it is, however, possible to cause shift of such box element towards the right in Figure 5 by a force sufcient to overcome the pre-loading of the spring 61. The amount of such possible movement against the spring will of course depend on the openness of the spring prior to overcoming Iits pre-loading. This possibie movement is made sufficient to meet the requirements of design presently to be explained.

The box element S4 is connected to the carrier top 43 by a link arrangement. This includes the link 62 having one end pivotally connected to the box element by the pin 63. The other end of this link is pivotally connected to a crank arm 64 by the pin 65. This crank arm is connected by a stub shaft (in the form of the pin 66) which extends up through the top plate 43 of the carrier; and we have shown a small plate or block 67 welded or otherwise secured to the underside of said top plate 43 to give additional bearing for such stub shaft 66. A lever arm 68 is secured to said stub shaft above the top plate 43, and its end is provided with a handle 69 by which such lever arm may be rocked through substantially 18() degrees or slightly more, to effect corresponding rock of the crank 64 between two extremes of movement. The parts are so designed that during such 180 degrees of crank rock the relative positions of the box element 54 and the carrier are shifted by an amount sufcient to ensure that movement of the idler wheel (presently to be described) will take up any slack existing in the abrasive band, and also cause some shift of the box element rightwardly in Figure 5 to thus bring the spring into some further degree of compression. During this latter movement (of the box element rightwardly from the nut in Figure 5) the compressive force of the spring is increased, and also there is established a freedom of movement between the box element and the nut, so that the box element may shift slightly leftward as and when needed to maintain the abrasive band continuously under spring tension.

At this point is should also be pointed out that once the condition just above stated has been attained, with the band under spring tension, the amount of such spring tension may also be adjusted from time to time by merely rotating the shaft 48 in the proper direction for either increase or decrease 'of such tension in the band. The parts are so proportioned and designed as to allow for the amount of such adjustment which experience shows to be necessary or desirable.

It is also noted that, when the shaft 48 has once been rotated to establish the desired degree of tension in the band, for normal operations, if it should become desirable or necessary to fully release the band from the wheels, such release may be quickly effected by throwing the lever 68 clear over through 180 degrees of rock, thus reversing the position of the crank 64 and allowing such an amount of movement of the carrier towards the right in Figure 5 as will ensure full release of the band tension, and in fact produce an amount of slack in the band to enable removal of the band from the wheels if desired. Thereafter restoration of the lever 68 to its working position will again cause shift of the carrier towards the previous position, with corresponding restorai tion of the band tension to that value which had previously existed.

The idler crowned wheel is shown at 21 in various of the gures now `to be described. This idler wheel may be of any design and construction adapted to the present operations, but it should be a crowned wheel. We do not here illustrate nor describe the wheel construction in detail. However, the wheel illustrated includes the central hub tubular element '70 (shown in Figure 7 in particular, and also in Figure 2, and the wheel is provided with the crowned peripheral surface 71. We have provided -a wheel supporting rod or shaft '72 which extends through this hub element '70, and the anti-friction bearings, 73 and 74 such as ball bearings are set onto the rod 72 and with their outer raceways set into such hub element 70 in convenient manner. It is desirable, and in some cases necessary, that at least a portion of the rod or shaft 72 be screw-threaded. In various of the drawings this shaft is shown as being thus threaded over its full length Valthough such full length threading is not needed for functional purposes. However, suitable rod may be secured which is pre-threaded to the desired threading, and at cost less than the cost of Unthreaded rod. Accordingly we have chosen to show this rod as being threaded over portions where such threading may, if desired, be eliminated. The bearing 73 is shown in Figure 7 in which figure wc have shown the set screw 75 for locking the inner raceway 76 of such bearing to the rod. We have also shown the rod as provided with the flattened portion 77 at the location of such bearing, against which flattened portion the set screw is locked. This flattening may be carried to the left-hand end of the rod in Figures 2 and 7, so that the inner raceway of the bearing 7d may also be locked to such flattened portion.

The wheel 21 is thus carried on the rod or shaft at a denite and unchanging position of said rod. We have provided, in the arrangement shown in Figures l to 8, inclusive, means to shift this rod endwise and at the same time to subject it to a controlled degree of rock during such endwise shift. ln Figure 3 we have shown three typical positions which the wheel 21 will assume by reason of such shift. The full line position is that in which the axis of this idler wheel lies substantially parallel to the axis of the drive or contact Wheel 20, and the two dashed line wheel positions shown in Figure 3 rep resent wheel positions at both sides of such central or parallel shaft position, and represent more or less extreme positions of Wheel shift and rock to both sides of such central position. We shall consider these several wheel positions more in detail presently, but here call attention to them as illustrative of functional operations which are to be performed by the structures now to be described in detail.

A bracket 70 is secured to the top d5 of the carrier and extends upwardly high enough to provide support for the rod or shaft 72 with proper clearance of the wheel 21 above the top of the carrier. Conveniently this bracket includes the angle bar 79 whose horizontal leg 80 rests on the top d3 of the carrier and may be secured to such top 4? as by the bolts 01. These bolts are so located that when desired the bracket 78 may be reversed for reasons to become apparent presently. To One end of this angle bar there is secured a vertical staff 32 (or 24), conveniently also comprising a section of angle bar as shown. Such sta may be secured to the angle bar 7.9 by welding or otherwise. This staff carries a yoke element comprising the two like Z-shaped elements 83 and` 84 the vertical lower legs of which are brought together and set against the face of the stal and secured thereto as by the bolts 85. The upper arms 86 and 87 of these Z-bars provide elements between which a wheel shaft control unit is journalled as will presently appear. The details of construction of this unit are shown in Figures 7 and 8 to which reference is now made We provide a box-like housing 80 conveniently in the form of an inverted U-shaped element whose downwardly extending sheets 89 and 90 constitute side walls of such housing. These side walls 09 and 90 are spaced apart to allow 'the box-like housing to seat nicely between the arms 36 and 07 as evident in Figures 1, 7 and 8. A sheet 91 is set into the end of this housing closest to the wheel 21 and another sheet 92 is set into the housing to the opposite side of an axis of housing swing to be presently referred to. These sheets 91 and 92 may be secured to the housing elements in convenient manner, as by spot welding or otherwise. These sheets 91 and 92 are also provided with the slight nipples 93 and 94 which are aligned with each other and are of size to pass the threads of the rod or shaft freely and without threading engagement with such threads. These nipples constitute simple bearings for engagement with the shaft or rod, and to maintain the rod and the housing in correct relationship and alignment with each other during the operations to be performed by the elements. The housing 88 is provided with means to journal it with respect to the arms 06 and 87 so as to permit needed rock of the housing about an axis extending through said arms. `Such journalling takes the form of the short studs or pins 95 and 96 which reach through both the side walls 89 and 90, and the arms 86 and 87, respectively, thus prd# viding a horizontal axis which includes both of such studs or pins. We shall presently show further functions of these studs or pins affecting the adjusting operations.

The end of the rod or shaft 72 opposite to the wheel location is pivotally connected to the upper end 0f a link 97, the lower end of such link being pivotally conu nected to a bracket 93 which extends from the staff 82, such pivoting being effected by the pin 99. In the form or embodiment shown in the figures now being described the rod or shaft 72 does not rotate. Accordingly we conveniently effect the pivotal connection of the upper end of the link 97 to such rod 72 by slotting the rod, extending the upper end of the link through such slot, and extend ing the pivot pin 100 through the rod and through the link. Thus this link also serves the function of retaining the rod against rotation while establishing the connection to the link.

Examination of the structures thus far described will show that endwise movement of the rod or shaft may be produced without its rotation. Such endwise rod movement will carry the wheel 21 with the rod, and since the bearings for such wheel are locked to the rod as already explained it .follows that the extent of lateral movement or adjustment of the wheel may be determined by the extent of rod endwise shift. lt is also apparent that as the rod is shifted endwise it must suffer a tilting displacement. This is true since the axis of rock extending bctween and including the studs or pins and 96 intersects the axis of the rod or shaft so that tilt may occur about such axis, and at the same time the pivotal connection between the upper end of the link .and the end of the rod must travel about a circular arc drawn about the pivotal point 99 of the lower end of the link. Thus the end of the rod must suffer a rising and/or falling movement as it is shifted endwise. Such rising and/or falling movement will be effected at that end of the rod to the opposite side of the staff and pivotal axis of the studs 95 and 96. Furthermore, the amount of such rising and falling effect will be retiected to the rod at a varying distance from the axis through the studs or pins 95 and 96, so that a special relationship between the rocking effect on the rod and the extent of the endwise shift of the rod must occur. At this point we merely call attention to the fact that a rocking effect combined with the endwise rod movement is produced, and such combined movement is reflected in the wheels position laterally as well as in its tilt.

We have provided means to effect endwise shift of the rod or shaft 72 as follows:

The nut 101 is threaded onto the rod or shaft and may be rotated without permission of endwise movement of such nut. The bevel gear element 102 is set into the housing 88 between the sheet 91 and said nut 101 and said gear is secured to the nut. To this end the nut is provided with a shouldered nipple 103 onto which the gear is set, and then the gear and nut are permanently secured together' as by welding as shown in Figure 7. The companion bevel gears 104 and 105 are set onto the inner ends of the studs 95 and 96 and riveted to said shafts as shown. These gears mesh simultaneously with the gear 102. Thus rotation of either of the studs 95 and/ or 96 will effect rotation of the gear 102, with corresponding rotation of the nut and threading engagement and action on the threaded rod or shaft. We place a disk 106 onto the shaft adjacent to the nut 101 at that side of said nut opposite to the gear 102. This disk is provided with the slight nipple 107 to give bearing support on the shaft, but such nipple is not threaded to the shaft. Another similar disk 108 is also placed on the shaft at a further location away from the gear 102, being provided with the slight nipple 109, and a sleeve is set onto the shaft between the nipple 107 of the disk 106 and the disk 10S so as to retain these parts at proper spacing. The slight nipple 109 of the disk 108 cornes into spacing engagement with the nipple 94 of the sheet 92 already referred to. None of the disks 106 or 103, or the nipples 107 or 109, is threaded to the shaft, but may rotate freely thereon if needed. Both of the disks 106 and 1% are of such size as to nicely retain the gears 104 and 105 at proper spacing from the rod or shaft and from each other, such fact being evidenced in Figure 8. The arrangement thus described is such that desired rotation of the gear 192 may be effected by rotation of either' of the studs 95 and/ or 96 as desired.

lt is now evident that we have provided simple means to effect the necessary endwise movements of the rod or shaft to produce lateral shift of the idler wheel; and have also provided means to effect rock of such rod or shaft about a horizontal axis during such endwise shift. Presently we shall analyze in further detail the relationship between these two kinds of wheel adjustment, and the effects thereof on the ruiming of the abrasive band.

The inner bearing raceway of the bearing '73 is stationary-that is, it does not rotate since the rod or shaft 72 does not rotate, and also the nipple 93 from the sheet 91 is stationary in the sense that it does not rotate with the wheel. We avail ourselves of these facts to provide a protection of the threaded rod or shaft section which travels into and out of the nut 101 to protect such threads against ingress of dust and other foreign material. For this purpose we have shown the light spiral spring element 1103d having its ends of reduced size and set onto the bearing element 76 and onto the nipple 93, respectively. We have also provided the loose dust-proof envelope 111 set over the convolutions of this spring element and with its ends drawn down close to the elements 76 and 93, respectively. This envelope is of sufficient length to extend between said elements 76 and 93 when the rod or shaft has been projected fully towards the left in Figure 7, thus maintaining the dust protection for the full necessary adjustment movement of said parts.

it is now noted that the arrangement of the parts as shown in Figures l to 4, inclusive, is for a right-hand set-up to which we have previously referred. Such fact will be evident from examination of Figures ll and l2 in comparison to the arrangement of the parts shown in said Figures l to 4. However, in case is should be desired to change the unit of Figures l to 4 to a left-hand set-up such change could be readily made by removing the bracket element 78 from the top of the carrier 42 by removing the bolts Si, and after reversing said bracket element on the carrier top, securing it again in place in such reversed condition. This operation will bring the idler wheel 21 to the right-hand side of the unit when i viewed as in Figure 3, or to the left-hand side of said unit when viewed as in Figure 4 which latter direction of viewing is that of the operator who stands at the location of the contact wheel when said wheel is located in the relative position shown in Figure ll and l2. it should be noted, however, that under such reversed condition of set-up the drive to the driving or Contact wheel in Figures ll and l2 would be from the opposite side of the band from that shown in said figuresthat is, the driving motor would then be located at the side of the viewer of Figure l2 instead of the side as there shown.

It is also to be noted that when the bracket element 78 is reversed as above explained, the stub shafts 95 and 96 would interchange positions, 'so that the stub shaft 96 j would then face the operators stand instead of the stubshaft 95 as previously. Then the flexible shaft controlling the lateral shift and the tilt of the idler wheel would he connected to said stub-shaft 95 instead of 95. Such dexible shaft is shown at 112 in Figure ll, and it is brought to a location close to the opera tors stand for ready manipulation similarly to the manipulation of the control for the tension o the band by use of the flexible shaft 52.

Reference is new invited to Figures 9 and l@ in which we have shown a modified arrangement 'for effecting the kcombined lateral and tilting or rocking shifts of the idler 12 wheel. In these figures the base section and carrier are both shown and are of the general construction as previously described. The barcket element 113, which is set onto and secured to the top 43 of the carrier, includes the angle bar section 11d having its horizontal leg set into facial contact with the top of the carrier, and secured thereto by the bolts 115, as in the previous construction. The staff 116, in the form of a section of angle bar is secured to a plate 117 which sets against one face of the vertical leg of the angle bar 114, and a pivotal connection established for this plate i117 with respect to the angle bar by the through bolt 118 extended through both said parts. By slightly loosening the nut 119 on this bolt the plate may be permitted to rock about a horizontal axis (namely, the bolt 11S), and then by tightening such nut the plate 117 may be locked in an adjusted position of rock. The rod 12d extends in more or less horizontal direction from the upper end of the staff 116, being secured to the staff in convenient manner,

as by welding, as shown in Figure 9. The idler crowned wheel 21a is journalled on this rod 124i in suitable manner, as by such bearings as are shown in Figures 2 and 7, so that said wheel is free to rotate on the rod, but must follow the endwise adjustments and the tilts of the rod faithfully. By releasing the nut 119 and then tilting the plate 117 it is evident that lateral shifts of the wheel will be effected, accompanied by corresponding tilts of the wheel and the plane which includes the wheel crown.

An angie shaped bracket element 121 has its vertical arm 122 secured to the face of the staff 116, as by welding or otherwise. This bracket element includes the outwardly extending horizontal arm 123 from which depend the two spaced apart arms 12d and 125. The short shaft 126 is journalled in these two arms 12d and 121:3', conveniently by setting the end portions of such shaft into short notches 12:7 formed in the arms 12d and 125, as shown in Figure 10, prior to securing the bracket element 121 to the staff. The shaft is shouldered at the locations of the arms 12d and 125 so as to prevent endwise shift of the shaft when it is rotated. The central portion of this shaft is threaded as shown in Figure 9, and the end portions of the shaft project beyond the arms 124 and 125 and are provided with the transverse holes by which suitable exible shafting may be connected to the one or the other of such projecting shaft portions for rotation of the shaft to produce the desired adjustments, as will presently appear.

A bell-crank lever 128 has its elbow pivoted to the face of the staff 116 by the pivot pin 129. The vertical arm 13h of this bell-crank carries the block 131 which extends outwardly between the arms 124 and 125 and through which block the shaft extends and the threaded portion of the shaft threads through this block so that rotational movements of the shaft produce movements of the block 131 towards one of the arms and from the other arm 125, or vice versa, depending on the direction of shaft rotation. Such lateral movements of the block 131 produce corresponding rocking movements of the bell-crank on its pivot 129 as will be at once apparent. lt is here noted that the arms 12d and 12S are set out far enough from the face of the staff 116 to permit proper freedom of rocking movement of the bell-crank as above explained without interference between the parts for the desired range of bell-crank rocks.

A lug 132 is secured to the bracket element 114, and extends therefrom as shown in Figure 9 at a location adjacent to the horizontal arm 133 of the bell-crank, as well shown in Figure 9. A stud 13d is secured to this lug 132 and extends through the slotted openings 135 formed in the end portion of the arm 133. Accordingly, this stud serves as a fixed abutment with which such arm 133 must cooperate, and thus Vrises the location of the free end of such bell-crank arm during rocks of the bell-crank in either direction of rock. The slot is of suflicient length to ensure proper cooperation with the stud 134 during all necessary rocking movements of the bell-crank.

Analysis of the foregoing structures will show that any rocking movement of the bell-crank, with the free end of the horizontal arm 133 in engagement with such fixed location stud, must result in a movement of the pivotal point 129 of the bell-crank, up or down as the case may be. Such up or down movement of the point 129 will produce corresponding movement of the staff element 116 to which such pivotal point is secured, thus bringing about the desired tilting movement of such staff, and to which we have previously referred. 1t is, of course, understood that the nut 119 shall have been loosened on the bolt 118 (or shall be permanently loose thereon) in order to permit such adjusting movements to be produced.

Now it will also be evident that such operational movements as just above explained will produce slight angularities between parts at the locations of engagements of such parts, so that binding might occur between such parts and thus interfere with their proper functioning. How ever, we have allowed sufficient freedom of engagements between such parts as to avoid any such binding actions.

lt is also noted that the bracket element 113 may be set onto the top of the carrier 42 for either a right-hand or a left-hand set-up when using the embodiment shown in Figures 9 and 10, being thus similar to the embodiment shown in previous figures in this regard.

lt is also to be noted that in the embodiment of Figures 9 and 10 the adjusting movements are effected by the rocking of the plate 117 about the horizontal axis of the bolt 11S as a fixed center of rock. The relative lateral and tilting movements thus produced on the wheel 21 are somewhat different from those which are produced by the embodiment shown in Figures 1 to 8, inclusive. We shall discuss these facts presently.

ln each of the embodiments thus far described the lateral shift of the wheel is produced by endwise shift of a non-rotating rod or shaft, the endwise movement thereof being produced by rotation of a nut or other element threaded onto such rod or shaft, or by direct endwise movement produced by some other element but without shaft rotation. In Figures 13, 14 and l5 we have shown another modied arrangement in which the endwise rod or shaft movement is produced by rotation of such element, a nut or other element being in threading engagement with such rod or shaft, and being retained against displacement in the axial direction of such rod or shaft, Reference is now made to Figures 13, 14 and 15.

In the modification of Figures 13, 14 and l5 the staff 32 is shown, corresponding to previously described elements of such numbering; and this staff is carried by a carrier of suitable construction, such as previously described herein. The rod or shaft 72 is also shown, the same supporting the wheel (not shown in Figures 13, 14 and l5), such wheel being the idler crowned wheel 21 of previous descriptions herein. Such wheel is so carried by the rod or shaft that it must execute lateral movements or adjustments corresponding to the endwise shaft adjustments in manner already fully explained. It will then be understood that such wheel is journalled to the rod or shaft 72, but cannot shift endwise of such shaft.

In the present embodiment we have provided means to rotate the shaft itself by controlled operations of the operator when it is desired to effect wheel adjustments. To this end the shaft 72 is threaded through a suflicient portion of its length to take Care of the required amount of endwise shaft movement. The staff 82 carries a plate 136 to which are secured one or two threaded nuts 137 and 138 which are in threading engagement with the shaft. These nuts thus cooperate with the shaft for relative endwise movements. Said plate 136 is carried by the staff 82 by means of a pivotal connection in the form of a stud 139 extended through the plate 136 and the staff 82 as shown in Figure 14. With this arrangement, rotation of the shaft must produce endwise shift of the shaft through the nuts; and since the plate 136 is pivotally 14 mounted such endwise shift may be accompanied by rock or tilt of the shaft itself. The stud is shouldered as shown at 144 and a nut 145 is threaded to the position of such shoulder, thus avoiding any binding of the plate 136 against the staff 82 when the nut is drawn up tight.

A box-like structure 140 is set over the shaft which lies to the right of the stalf 82 (when viewed as in Figure 13), such structure taking the form of an inverted U-shaped sheet metal blank formed to provide the top 141, and the two sides 142 and 143. This boxlike struc* ture shifts back and forth with endwise movements of the shaft 72, as will presently become evident. The portion of such box-like structure which overlies the upper end of the staff 82, and the plate 136, and the nuts 137 and 133, and the pivotal connection 139, and the threaded shaft at the location of the nuts, will serve as a protection to said parts during the operations which they perform.

The box-like structure extends over the shaft for some distance at that side of the shaft opposite to the wheel location, comprising the extension 143e, as shown in Figure 13. This extension portion is provided with the end walls 147 and 148, such end walls being spot welded or otherwise secured to the side walls 142 and 143 at the location of the extension. Also, the side walls at such extension location are brought inwardly towards each other in their lower portions, to provide a floor for the extension, and are then formed downwardly in parallel flanges to provide the double thickness iange portion 149 which is preferably located directly below the central portion of the box-like structure extension, axially thereof. This flange portion is provided with one or more holes 151) through which may be passed a pivotal pin 151 such pivotal pin also extending through the upper end of the link 97EN which corresponds to the link 97 of a previous embodiment. The lower end of this link is pivotally connected to the lug 93a which is carried by the staff 32 as in the previously described embodiment.

The shaft 72 extends through both of the end walls 147 and 148, which end walls are conveniently provided with the slight nipples 152 and 153 to provide suitable journals for the shaft 72 at the locations where said shaft passes through such end Walls. This construction also ensures that the extension 140a and in fact the entire box-like structure will be retained in alignment with the shaft at all times. A bevel gear element 154 is set onto the shaft at the location of the end wall 148, or, as shown, is carried by a block .which is in turn set onto the shaft at such location. This is the block 155. This block is provided with the outwardly extending sleeve 156 onto which the bevel gear is slipped, and such sleeve also extends through and finds bearing in the nipple 153 already referred to. A nut 157 is threaded onto the extreme end of the shaft and serves to press against the said sleeve 156. The shaft is shouldered at 158 so that by drawing up the nut 157 the sleeve 156 and thus also the block is drawn tightly against such shoulder, thus locking the block to the shaft in driving manner. Nevertheless no binding action is produced on the nipple 156, the parts being properly proportioned to avoid such action. The bevel gear is preferably spot welded to the block 155 as shown so that a good driving engagement between these parts is assured.

The side walls 142 and 143 receive the stub shafts 159 and 160, corresponding in this respect to the stub shafts 95 and 96 of the previously described embodiment; and the bevel gears 161 and 162 are locked to the inner ends of these stub shafts 159 and 160, respectively, as shown in Figure 15. These bevel gears mesh with the bevel gear 154 so that said gear 154 may be rotated in either direction by drive from either of the stub shafts 159 or 160 as desired. The spacer plates 163 and 164 and the sleeves 165 and 166 are set between the bevel gears 161 and 162, and onto the shaft within the extension 140% thus corresponding to similar parts of the previously described embodiment.

It will now be seen that rotation of either of the stub shafts 159 or 160 must produce rotation of the shaft 72. Since said shaft is threaded to the nuts 137 and 138 it is seen that such shaft rotation must act to produce endwise movement of the shaft with respect to the said nuts, and thus with respect to the staff 82, It will also be seen that endwise movement of the shaft as thus produced must be accompanied by a like movement of the extension 14da and thus of the box-like structure as a whole, since the block 155 which is secured to the shaft cannot shift endwise within the extension 140a more than permitted by necessary tolerances. lt is also seen that during such movement of the extension 140a said extension must remain axially in alignment with the shaft due to the shaft engagement with both of the end walls 147 and 148, or their nipples 152 and 153. Accordingly, endwise movement of the shaft by the threading engagement of the shaft with the nuts 137 and 138 causes corresponding endwise movement of the extension 1408; and due to the presence of the link connection to that extension it follows that a tilting action will be produced during such shaft endwise movement.

By selecting the proper one of the holes 150 of the ange element 149 the relative tilting and endwise movements may be brought to a desired relation, so that the proper tilt of the wheel will be produced as the lateral movement occurs.

lt is now evident that each of the embodiments disclosed herein produces endwise shift of the idler crowned wheel, accompanied by tilt of such wheel. It is also evident that such tilt is produced about a substantially horizontal axis-that is, such tilt is a tilt in which the plane embracing the crown of the wheel, and in which plane such crown is contained, is rocked about a substantially horizontal axis. Reference may be had to Figure 12 in which we have indicated the plane of the crown of the wheel Z1 by the dashed line 16'7. Each of the embodiments herein disclosed is such that lateral shift of the wheel 21 (towards or away from the observer in Figure 12) must be accompanied by tilt of this plane 167 about a substantially horizontal axis, or an axis which is substantially parallel to the plane of the top 43 of the carrier 42. Such tilt of the wheel is accompanied by a slight twist of the belt or band in its runs between the two wheels 2t) and 21; but it is important to observe that such a form or kind of tilt (about such substantially horizontal axis) is one in which the projection of the said plane 167 to the location of the wheel Zti still ensures 'i intersection of that plane with said wheel 2i) for all conditions of such tilt. Thus there is produced no misalignment of the belt or band as it travels around its arc of contact or engagement with the idler wheel 21, and perfect running will occur, even for substantial amounts of such tilt.

Such arrangements are to be clearly distinguished from arrangements in which the idler wheel is tilted about an axis which extends vertically or substantially vertically. Such a distinguished arrangement, different from those herein disclosed, causes the plane of the wheel crown of the idler wheel to shift to one end or the other of the driving wheel, as the idler wheel is thus tilted about a vertical axis; `and there is substantially only a single adjustment of such vertical axis tilt arrangement in which the projection of the idler wheel crowns plane will intersect thc driving Wheel, being the normal or untilted condition of the idler wheel.

We have referred to the ability to vary the relative tilting and lateral movements which will be produced by selection of one or another of the holes 150 as the pivotal point for the upper end of the link 97a in the embodiment shown in Figures 13, 14 and 15. tudy of the various embodiments herein disclosed will show that the relation of the tilting movement in comparison yto the lateral movement of the wheel is subject to certain functional relationships of the parts controlling these movements. In Figure 3 we have shown the crowned wheel Z1 in its more or less central position by full lines. We have also shown a leftwardly rocked position of this Wheel to be the dashed lines as designated as 21a, and a rightwardly rocked position of such wheel by the dashed lines as designated as Zlib. These two positions 21a and 2lb may be considered as approximately extreme left-hand and right-hand. positions of adjustment. We have shown in Figure 3 the path of travel of the top of the crown by the line M3, and the path of travel of the bottom of the crown by the line 169; and the path of travel of the center of rotation of the wheel is shown by the line ii'i. it is seen that all three of these lines indicate travel of of said portions of the wheel in the same lateral dir `tion duri any change of lateral wheel position and corresponding change of tilt. in Figure 10 we have similarly indicated the paths of travel of the top of the wheel crown, the bottom of said crown, and the center of wheel rotation for the modified embodiment which is shown in Figures 9 and 1t), such paths being shown by the dashed lines E71, 1172, and 17? for the three wheel positions .lcg Zib, and 2li/C, respectively. (lt is noted that in Figure l0 the line 17E has been lowered to bring it within the confines of the drawing, but such lowering has been effected without change of the form of the curve, nor change of the values of the curves points nor their lateral locations.)

Comparison of the curves of Figures 3 and l() reveals that in each case the top and bottom portions of the wheei crown both travel in the same direction during any adjustment, 'out at different rates, so that both the top and bottom runs of the belt or band are always shifted in the same direction. @f course the exact forms of these curves will be affected by various proportional dimensions of the designs for which the curves are prepared, but we have above pointed out a characteristic which is peculiar to both of the embodiments to which such curves relate. Similar curves could also be prepared for the embodiment shown in Figures 13, 14- and 15, and it would reveal similar fundamental characteristics.

We claim:

l. The combination with a cylindrical surface drive wheel and means to journal said wheel for rotation on its axis and means to drive said wheel, and an abrasive surface belt travelling on the cylindrical surface of said drive wheel and supported by said cylindrical surface, of means to maintain said belt element in driving engagement with said drive wheel cylindrical surface and to control the location of running engagement of said belt element with said surface, comprising a crowned surface idler wheel located in proximity to but separated from the drive wheel and with the crowned surface of said idler wheel in belt ruiming alignment with the drive wheel, the belt element travelling directly between the idler wheel crowned surface and over the drive wheel cylindrical surface during belt running engagement with the two wheels, means to journal the idler wheel, and to control tracking of the belt on the drive wheel, said means comprising a rod, a journal mounting the wheel on the rod at a position fixed longitudinally of the rod, a support for the rod at one side of the wheel journal mounting, a fixed pivotal mounting for said rod support, the axis of said pivotal mounting being substantially parallel to the belt runs approaching and leaving the idler wheel and intersecting the projected axis of idler wheel rotation, the rod being endwise movable through the rod support, means to move the rod longitudinally through the rod support to thereby laterally adjust the location of the crown of the wheel, and means to cause the rod and the rod support to tilt about said fixed pivotal mounting during such endwise movement of the rod, to thereby rock the plane which includes the apex of the crown of the idler wheel in comparison to any plane which is normal to the axis of rotation of the drive wheel.

2. Means as specified in claim 1, wherein the fixed pivotal mounting for said rod support comprises a carrier, means to support said carrier including means permitting carrier movement in direction substantially para]- lel to the path of belt travel between the idler wheel and the drive wheel, and means to move the carrier with respect to the carrier support.

3. Means as specified in claim 2, wherein the means to move the carrier with respect to the carrier support includes a movable operator controlled element.

4. Means as specitied in claim 3, together with yieldable spring means between the carrier supporting means and the carrier and acting to urge the carrier in direction to move the idler wheel away from the drive wheel for exertion of tension on the belt element.

5. Means as specied in claim 4, wherein the operator controlled element includes means to adjust the urging force of the spring means.

6. Means as specified in claim 2, wherein the means to move the carrier with respect to the carrier support includes spring means urging the carrier in direction to move the idler wheel yaway from the drive wheel.

7. Means as specied in claim 3, wherein the movable operator controlled element for the means to move the carrier with respect to the carrier support includes a manually controlled element at a location in proximity to the driving wheel.

8. Means as specified in claim 7, together with manual means to actuate the means which causes lateral movement of the journal movable means to adjust the lateral position of the idler wheel journal means, including a manually controlled element at a location in proximity to the driving wheel.

9. Means as specified in claim 1, wherein the means to tilt the idler wheel journal means acts to produce tilt of such journal means in direction to produce a lateral rocking movement of the crown of the idler wheel at the top of said wheel in the same direction `as the direction of lateral movement of the journal means of the idler wheel.

l0. Means as specied in claim 1, wherein the means which causes the rod and the rod support to tilt about said fixed pivotal mounting during the endwise movement of the rod acts to produce tilt of such journal means in direction to produce lateral rocking movement of the crown of the idler wheel at the top of said wheel in the same direction as the direction of lateral movement of the journal means of the idler wheel.

1,1. Means as specified in claim 1, wherein the means to cause lateral movement of the idler wheel journal means and the means to tilt the idler wheel journal means simultaneously are constituted to produce lateral movement of the top of the crown of the idler wheel and lateral movement of the bottom of the crown of the idler wheel both in the same direction as the direction of lateral movement of the journal means of the idler wheel.

l2. Means as specified in claim 11, wherein the amount of the lateral movement of the top of the crown of the idler wheel in the direction of lateral movement of the journal means of the idler wheel is greater lthan the amount of the lateral movement of the bottom of the crown of the idler wheel in `said direction. of lateral movement of the journal means of the idler wheel for any movement of the journal means of the idler wheel.

13. Means as specified in claim 1, together with manual means to actuate said means which causes lateral movement of the journal supporting movable means to adjust the lateral position of the idler wheel journal means.

14. Means as specified in claim 13, wherein said manual means to actuate the means which causes the lateral movement of the journal supporting movable means includes a manually controlled element at a location in proximity to the driving wheel.

References Cited in the le of this patent UNITED STATES PATENTS 344,835 Hollister July 6, 1886 832,889 Wysong Oct. 9, 1906 918,247 Wysong Apr. 13, 1909 1,149,479 Townsend et al. Aug. 10, 1915 1,179,999 Blevney Apr. 18, 1916 1,228,856 Washburn June 5, 1917 2,313,254 Mead Mar. 9, 1943 2,368,848 Krueger Feb. 6, 1945 2,407,499 Klossner Sept. 1, 1946 2,449,519 Sutton Sept. 14, 1948 2,507,372 Emmons May 9, 1950 2,578,662 Bader Dec. 18, 1951 2,637,952 Reed May 12, 1953 

